By GENE STOUT, P-I MUSIC CRITIC

Updated 10:00 pm, Monday, September 10, 2007

Last year, Colbie Caillat was working at a tanning salon and singing in small clubs. Today, the dusky-voiced, 22-year-old singer-songwriter from Malibu, Calif., is a bona fide pop star.

It wasn't "American Idol" that propelled the quintessential California girl to fame. It was MySpace.com.

On the strength of her song "Bubbly," a breezy, acoustic-pop tune about young love, Caillat became the top unsigned artist on the social-networking Web site for four months, after a friend created a page for her last September at myspace.com/colbiecaillat.

Caillat (pronounced cal-LAY) has since signed to Universal Republic Records, which released her debut album, "Coco," last month. "Bubbly," the first single, is at No. 59 this week on Billboard's Hot 100 singles chart and at No. 34 on the Hot Digital Songs chart.

While growing up in Malibu, Caillat learned about the music business from her father, Ken Caillat, who co-produced the "Rumours" and "Tusk" albums for Fleetwood Mac. Until she discovered MySpace, she was writing songs just for fun.

To date, Caillat has nearly 180,000 "friends" and more than 18 million song plays on MySpace, making her a true Internet phenomenon. She recently finished a tour with the Goo Goo Dolls and is on her own headlining tour, which includes a show with Vicci Martinez and Tyrone Wells Tuesday at Showbox at the Market.

On becoming a MySpace phenomenon:

I was completely surprised. I didn't even know about the whole MySpace thing. My friend made the page and uploaded the songs for me. I was like, "OK, cool." But once I started getting messages from people all over the world telling me what my songs meant to them, I thought, "Wow, this is great."

On adjusting to her new life as a pop star:

It was overwhelming a few weeks ago because I didn't realize what I'd gotten myself into. I didn't realize that I'd have such a crazy schedule and that I wouldn't be going home for a while. I was scared. I was scared to perform. But now that I'm prepared, I'm really excited.

On having her dad's help in the studio:

He was there almost the whole time. He brought in so many ideas for (producer) Mikal Blue and me. Mikal's a great producer, but he's pretty new at it and my dad sort of showed him the old techniques from back in the day. I really wanted him to be involved.

On writing in the bathroom:

I like to go in there and play because the acoustics are so great. It echoes, so when I'm performing I feel like, "Omigosh, I don't have to sing that loud because it carries so well."

On what makes her songs so appealing:

From what I hear, people just relate to them. They're so simple. People say every song reminds them of a relationship or a family problem or a battle with themselves.

I was taking an acting class in college a couple of years ago because I was really shy on stage and I really wanted to get better about that. But I quit the class (laughs) and then I wrote that song because I was really mad at myself for quitting.